How to add CSS to certain pages? Feed

Thanks. So on the feed page on mobile I want to remove the top section since it’s the users own info. I know it has the expand but really not needed on a page to view the posts of who the user follows.

The default there is also collapsed state where you have to expand them one by one. And if a post has an image it shows the url until it’s open. I want to make the feed visible instead of collapsed.